1. Field of the Invention
The present invention relates to a linear guide apparatus which can be used in the industrial machinery field, etc.
The present invention also relates to a linear guide apparatus which can be used in, for example, the industrial machinery field such as a machine tool or an injection molding machine.
Further, the present invention relates to a linear guide apparatus which can be used in, for example, the industrial machinery field such as a machine tool or an injection molding machine.
2. Description of the Related Art
FIG. 13 shows an example of a conventional linear guide apparatus of this kind.
The linear guide apparatus has a guide rail 1 which extends in the axial direction, and a slider 2 which straddles the guide rail 1 so as to be relatively movable in the axial direction.
In each of the side faces in the width direction of the guide rail 1, two rolling element rolling grooves 3 which elongate in the axial direction are formed. Namely, four rolling element rolling grooves are formed in total. In the slider body 2A of the slider 2, rolling element rolling grooves 5 respectively opposed to the rolling element rolling grooves 3 are formed in the inner side faces of wing portions 4.
A large number of cylindrical rollers 6 serving as rolling elements are rotatably charged between the opposed rolling element rolling grooves 3, 5. By means of rolling of the cylindrical rollers 6, the slider 2 is caused to be relatively movable on the guide rail 1 in the axial direction.
In accordance with the movement, the cylindrical rollers 6 which are interposed between the guide rail 1 and the slider 2 are rotated and moved toward an axial end portion of the slider 2. In order to enable the slider 2 to be continuously moved in the axial direction, it is necessary to endlessly circulate the cylindrical rollers 6.
Therefore, holes 7 which axially pass through the wing portions 4 of the slider body 2A are formed, and a circulation tube 8 the inner side of which is to be used as a path (rolling element path) 8a for the cylindrical rollers 6 is fitted into each of the holes 7. A pair of end caps 9 which are parts for circulating rolling elements are fixed respectively to axial ends of the slider body 2A by screws or the like. In each of the end caps 9, a direction change path 10 (see FIG. 1) which is curved in a semicircular arc-like shape so as to communicate the pair of opposed rolling element rolling grooves 3, 5 with the rolling element path 8a is formed, thereby forming an endless circulation raceway for the cylindrical rollers 6.
The large number of cylindrical rollers 6 which are endlessly circulated are rotated in the same direction about the respective roller axes. When adjacent ones of the cylindrical rollers 6 are in contact with each other, therefore, the directions of the roller velocities in the contact area are opposite to each other, and a force due to the opposite directions impedes smooth rotations of the cylindrical rollers 6.
Since the cylindrical rollers 6 are used as rolling elements, the rigidity and the load capacity are enhanced as compared with the case where balls are used. On the other hand, runout of the cylindrical rollers 6 during running of the slider, or so-called skew occurs to cause the operation ability to be lowered.
Under these circumstances, conventionally, a separator 20 is interposed between adjacent ones of the cylindrical rollers 6 so as to prevent the rolling rollers from being in direct contact with each other, and suppress the skew. According to the configuration, the slider 2 can smoothly run, and the noise level during running can be lowered.
Each of the separators 20 has: a separator body 21 which is to be interposed between adjacent cylindrical rollers 6; and arm portions 22 which are placed so as to sandwich the axial end faces of the cylindrical rollers 6, and which are integrated with the separator body 21. In the separator body 21, concavely curved faces corresponding to the outer circumferential shape of the cylindrical rollers 6 are formed in portions respectively opposed to the outer peripheral faces of the cylindrical rollers 6. In FIG. 13, 23 denotes separator guide members which are placed between the outer side faces of the guide rail 1 and the inner side faces of the slider 2.
When the cylindrical rollers 6 are circulated through the pair of rolling element rolling grooves 3, 5, the direction change paths 10, and the rolling element path 8a, the arm portions 22 of the separators 20 are guided along the circulation direction of the cylindrical rollers 6 by the separator guide members 23, and guide grooves 24 which are formed in the rolling element path 8a and the direction change paths 10.
In the conventional linear guide apparatus, each of the guide grooves 24 has an identical width in all of regions where the cylindrical rollers 6 are linearly moved, and those of the direction change paths 10. When the guide groove 24 is set so as to have a width which is ideally suitable in the linear motion regions, therefore, the arm portions 22 of the separators 20 interfere with the guide groove 24 in the direction change regions.
To comply with this, conventionally, the width of the guide groove 24 is set to a value which enables the arm portions 22 to be moved without interfering with the guide groove 24 in the direction change regions. The width is set as that of the guide groove in all the linear motion regions and the direction change regions.
In this configuration, however, the width of the guide groove 24 in the linear motion regions is larger than that in the ideal state, and hence the gaps between the arm portions 22 of the separators 20 and the guide groove are excessively large in the linear motion regions.
In each of the endless circulation raceways, each separator 20 and the corresponding cylindrical roller 6 are moved with being pushed by the rear cylindrical roller 6. In the case where the gaps between the arm portions.22 of the separators 20 and the guide groove are excessively large in the linear motion regions, therefore, the separators 20 may produce a zigzag motion to largely change the axis-to-axis distance of adjacent ones of the cylindrical rollers 6. As a result, the operation ability may be impaired.
In the conventional linear guide apparatus, each of the guide grooves 24 has an identical width in all of regions where the cylindrical rollers 6 are linearly moved, and those of the direction change paths 10. In the linear motion regions, therefore, each cylindrical roller 6 is in close contact with the concavely curved face of the separator body 21 of the corresponding separator 20, and the arm portion 22 is smoothly guided along the guide groove 24.
When the separator 20 enters the R-arcuated direction change region to be inclined as shown in FIG. 18, however, the arm portion 22 of the separator interferes with the inner peripheral wall of the guide groove 24 (see FIG. 19), thereby disabling the cylindrical roller 6 to be circulated in a state where it is in close contact with the concavely curved face of the separator body 21. As a result, problems such as that the intervals of the cylindrical rollers 6 fluctuate to cause vibrations to be easily produced, and that the life period of the separator 20 is shortened may arise.
FIG. 48 shows an example of a conventional linear guide apparatus of this kind.
The linear guide apparatus has a guide rail 101 which extends in the axial direction, and a slider 102 which straddles the guide rail 101 so as to be relatively movable in the axial direction.
In the guide rail 101, two or upper and lower rolling element rolling grooves 103 which elongates in the axial direction are formed on each of side faces in the width direction, or namely four rolling element rolling grooves are formed in total. In the slider body 102A of the slider 102, two or upper and lower rolling element rolling grooves 105 respectively opposed to the rolling element rolling grooves 103 are formed on the inner side face of each of wing portions 104, or namely four rolling element rolling grooves are formed in total.
A large number of cylindrical rollers 106 serving as rolling elements are rotatably charged between the opposed rolling element rolling grooves 103, 105. By means of rolling of the cylindrical rollers 106, the slider 102 is caused to be relatively movable on the guide rail 101 in the axial direction.
In accordance with the movement, the cylindrical rollers 106 which are interposed between the guide rail 101 and the slider 102 are rotated and moved toward an axial end portion of the slider 102. In order to enable the slider 102 to be continuously moved in the axial direction, it is necessary to endlessly circulate the cylindrical rollers 106.
Therefore, two or upper and lower holes 107 which axially pass through each of the wing portions 104 of the slider body 102A are formed in the wing portion 104, or four holes are formed in total. A circulation sleeve 108 the inner side of which is to be used as a path (rolling element path) 108a for the cylindrical rollers 106 is fitted to each of the holes 107. A pair of end caps 109 which are parts for circulating rolling elements are fixed respectively to axial ends of the slider body 102A by screws or the like. In each of the end caps 109, a direction change path 110 (see FIG. 49) which is curved in an arc-like shape so as to communicate the pair of opposed rolling element rolling grooves 103, 105 with the rolling element path 108a is formed, thereby forming an endless circulation raceway for the cylindrical rollers 106.
As shown in FIG. 49, each of the end caps 109 has: an end cap body 109a; and a first return guide 130 and a second return guide 140 which are fitted in the axial direction to the side of the end cap 109 which faces the corresponding end face of the slider body 102A.
The first return guide 130 and the second return guide 140 are formed as plate-like members having a substantially same outer shape. Plural projections, recesses, and holes for forming the direction change paths 110 are disposed in parallel joining faces which are opposed to each other and outer side faces. The joining faces of the first return guide 130 and the second return guide 140 are joined together so that projections and recesses are fitted and their outer shapes substantially coincide with each other. Under this state, the first return guide 130 is axially fitted to the end cap body 109a (for example, see JP-A-2002-54633).
In this example, the first return guide 130, the second return guide 140, and the end cap body 109a form a direction change path 110 through which the upper rolling element path 108a communicates with the lower pair of rolling element rolling grooves 103, 105, and the first return guide 130 and the second return guide 140 form a direction change path 110 through which the lower rolling element path 108a communicates with the upper pair of rolling element rolling grooves 103, 105.
The large number of cylindrical rollers 106 which are endlessly circulated are rotated in the same direction about the respective roller axes. When adjacent ones of the cylindrical rollers 106 are in contact with each other, therefore, the directions of the roller velocities in the contact area are opposite to each other, and a force due to the opposite directions impedes smooth rotations of the cylindrical rollers 106.
Since the cylindrical rollers 106 are used as rolling elements, the rigidity and the load capacity are enhanced as compared with the case where balls are used. On the other hand, runout of the cylindrical rollers 106 during running of the slider, or so-called skew occurs to cause the operation ability to be lowered.
Under these circumstances, conventionally, a separator 120 is interposed between adjacent ones of the cylindrical rollers 106 so as to prevent the rolling rollers from being in direct contact with each other, and suppress the skew. According to the configuration, the slider 102 can smoothly run, and the noise level during running can be lowered.
As shown in FIGS. 50 to 52, each of the separators 120 has: a separator body 121 which is to be interposed between adjacent cylindrical rollers 106; and arm portions 122 which are placed so as to sandwich the axial end faces of the cylindrical rollers 106, and which are integrated with the separator body 121. In the separator body 121, concavely curved faces 121a corresponding to the outer circumferential shape of the cylindrical rollers 106 are formed in portions respectively opposed to the outer peripheral faces of the cylindrical rollers 106. In FIG. 48, 23 denotes separator guide members which are placed between the outer side faces of the guide rail 101 and the inner side faces of the slider 102.
When the cylindrical rollers 106 are circulated through the pair of rolling element rolling grooves 103, 105, the direction change paths 110, and the rolling element path 108a, the arm portions 122 of the separators 120 are guided along the circulation direction of the cylindrical rollers 106 by the separator guide members 123, and guide grooves 124 which are formed in the rolling element path 108a and the direction change paths 110.
In the conventional linear guide apparatus, both the first return guide 130 and the second return guide 140 are formed as plate-like members having a complex and substantially same outer shape, and the plural projections, recesses, and holes for forming the direction change paths 110 are disposed in the parallel joining faces which are opposed to each other and the outer side faces. Therefore, the shapes of the guides are complicated and require a high molding accuracy. Moreover, the work of fitting the projections and recesses of the joining faces of the first return guide 130 and the second return guide 140 so that their outer shapes substantially coincide with each other is cumbersome. As a result, the efficiency of the assembly work is poor, and the production cost is high.
The end cap body 109a, the first return guide 130, and the second return guide 140 have a structure in which these components are split from one another in a substantially parallel manner. Therefore, there are many split planes which cross the roller raceway groove of the direction change path 110 in the roller axis direction (two split planes between the first return guide 130 and the second return guide 140, and one split plane between the first return guide 130 and the end cap body 109a, or three split planes in total). As a result, the number of steps in joining portions in the split planes is increased, thereby causing the possibility that the guiding accuracy of the cylindrical rollers 106 is impaired and the operation ability is adversely affected.